I went through a dozen of my apps and It seems that the test adUnitID provided by Admob in their documentation doesn't seems to work anymore and the ads will not show unless you provide an adUnitID generated for publishing.(from Admob dashboard).
Please is this happening for other people or am I missing some new changes that Admob recently made to load test ads?
This is the admob test ID and I code that used to work: self.bannerView.adUnitID = @"ca-app-pub-3940256099942544/2934735716";
PS. The banner test ID was working yesterday.